JP7127117B2 - SEALANT RESIN COMPOSITION, LIDING MATERIAL, AND PACKAGE - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sealant resin composition, a lid material, and a package.

Resin compositions for sealants are widely known to be used as one of packaging or sealing means.
In particular, impact-resistant polystyrene sheets, polyethylene-laminated paper, foamed polystyrene sheets, and impact-resistant polystyrene films bonded to these sheets are widely used as container materials for foods and pharmaceuticals. Materials are known to be sealed by heat sealing using resin sealant compositions.

An easily peelable resin layer containing a metal layer, an adhesive layer, a resin comprising at least one of an ethylene-vinyl acetate copolymer resin, an ethylene-acrylic acid ester copolymer resin and a polyolefin resin, and a tackifier. There is known a laminate for an easily peelable packaging material having a laminate obtained by sequentially laminating the above (for example, JP-A-3-79342).

On the other hand, when the resin composition as described above is used as a sealant for food lids, it may not meet the standards of the country where it is used.

As disclosed in JP-A-3-79342, a resin composition obtained by blending an olefinic resin and a tackifying resin is known as a resin formulation used as a sealant. The tackifying resin contained in generally has a high elution amount in hexane.
Therefore, when trying to apply a resin composition containing a certain amount of a tackifying resin to a food container, there is a risk that it will not satisfy national standards such as food hygiene standards in each country.
The problem to be solved by the present invention is to provide a sealant resin composition, a lid material, and a packaging body, in which the amount of elution into hexane is suppressed while maintaining good seal strength as compared with conventional sealant resin compositions. to do.

Specific means for solving the above problems include the following aspects.
<1> An ethylene/unsaturated ester copolymer (A) and an ethylene/(meth)acrylic acid alkyl ester copolymer (B) different from the ethylene/unsaturated ester copolymer (A) , with respect to the total content of the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B), the ethylene/unsaturated ester The content of the copolymer (A) is 10% by mass or more and 90% by mass or less, and the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 10% by mass or more and 90% by mass. % by mass or less, and the total molar amount of the structural units of the ethylene/unsaturated ester copolymer (A) and the structural units of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 100 mol% When the total content ratio of the structural units having a polar group contained in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is A sealant resin composition having a content of 5.0 mol % or more and 8.5 mol % or less.
<2> The sealant resin composition according to <1>, wherein the ethylene/unsaturated ester copolymer (A) is an ethylene/vinyl acetate copolymer.
<3> The sealant resin composition according to <1> or <2>, wherein the ethylene/(meth)acrylic acid alkyl ester copolymer (B) has 1 or more and 4 or less carbon atoms in the alkyl moiety.
<4> The sealant resin composition according to any one of <1> to <3>, wherein the content of the tackifying resin is less than 1% by mass.
<5> Content ratio X (mol%) of unsaturated ester-derived structural units in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester relative to the total molar amount The content ratio Y (mol%) of the structural unit derived from the (meth)acrylic acid alkyl ester in the system copolymer (B) satisfies all of the following formulas (1), (2) and (3) < The sealant resin composition according to any one of 1> to <4>.
Y>1 (1)
Y<-0.7X+7.1 (2)
Y>-0.7X+4.4 (3)
<6> The sealant resin composition according to <5>, which satisfies all of the following formulas (4), (5) and (6).
Y≧1.8 (4)
Y≤-0.7X+6.8 (5)
Y≧−0.7X+5.2 (6)
<7> The sealant resin composition according to any one of <1> to <6>, wherein the amount extracted into n-hexane as measured by the following test method is 30 mg/L or less.
(Test method)
A test piece is prepared which includes a substrate layer and a seal layer provided on one surface of the substrate layer and made of the sealant resin composition.
Next, the test piece is set in a single-sided elution jig, and the single-sided elution jig with the test piece set is immersed in an n-hexane solvent of V [L] and left at 25 ° C. for 2 hours. . Here, the amount of n-hexane solvent with respect to the surface area W [cm ² ] of the sealing layer of the test piece is V [L]=W/500. That is, the amount of n-hexane solvent is 2 mL per 1 cm ² of surface area of the sealing layer of the test piece.
Next, the n-hexane was distilled off from the obtained n-hexane extract, and the mass M [mg] of the extraction residue obtained by distilling off the n-hexane was measured, and the n-hexane Calculate the extraction amount Z (M/V) [mg/L].
<8> The sealant resin composition according to any one of <1> to <7>, which has a peel strength of 10 N/15 mm or more and less than 15 N/15 mm, as measured by the following test method.
(Test method)
A test piece is prepared which includes a substrate layer and a seal layer provided on one surface of the substrate layer and made of the sealant resin composition.
The test piece is laminated on the HIPS sheet so that the seal layer is in contact with the 0.5 mm thick HIPS (high impact polystyrene) sheet, and a 0.3 mm thick PET sheet is laminated on the test piece and laminated. got a body
A high-frequency welder (maximum output = 3 kW, oscillation frequency = 40.46 MHz) was used to weld the laminate at 52% or 54% output and 0.1 MPa (gauge pressure) for 2 seconds for a welding time of 0.5. After sealing for 2 seconds and cooling for 2 seconds, the PET sheet was removed and the test piece was adhered to the HIPS sheet and left at room temperature (23° C.) for 24 hours.
Next, in an environment of 23 ° C., the test piece (15 mm wide test piece) was pulled away from the HIPS sheet at a tensile speed of 300 mm / min, and the maximum stress was calculated as the peel strength [N / 15 mm] against the HIPS sheet. 9> A lid material comprising a substrate and the sealant resin composition according to any one of <1> to <8>.
<10> The lid material according to <9>;
and a bottom material to which the lid material is heat-sealed.

ADVANTAGE OF THE INVENTION According to this invention, the sealant resin composition, lid|cover material, and package which the elution amount to hexane was suppressed while favorable sealing strength is maintained are provided.

An embodiment that is an example of the present disclosure will be described below. The present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present disclosure.

In this specification, "-" in a numerical range means including the numerical values before and after "-". In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the values shown in the examples.
As used herein, the amount of each component in the composition refers to, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, the constituent units of the multiple substances present in the composition means

[Resin composition for sealant]
The sealant resin composition of the present disclosure comprises an ethylene/unsaturated ester copolymer (A) and an ethylene/(meth)acrylic acid alkyl ester different from the ethylene/unsaturated ester copolymer (A). and a copolymer (B), relative to the total content of the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) , the content of the ethylene/unsaturated ester copolymer (A) is 10% by mass or more and 90% by mass or less, and the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is The amount is 10% by mass or more and 90% by mass or less, and the structural unit of the ethylene/unsaturated ester copolymer (A) and the structural unit of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) When the total molar amount of is 100 mol%, a configuration having a polar group contained in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) The total content ratio of the units is 5.0 mol % or more and 8.5 mol % or less.

It is believed that the sealant resin composition of the present disclosure, which has the above configuration, can maintain good seal strength while suppressing the amount of elution into hexane.
In addition, the sealant resin composition of the present disclosure may contain other polymers and additives as necessary, but does not substantially contain a tackifying resin. Even if it is contained, it is preferably less than 1% by mass, more preferably less than 0.5% by mass, relative to the sealant resin composition.

The tackifying substance is also called a tackifier, and is used to increase the adhesive strength and tack strength of the base polymer. family petroleum resins, aromatic petroleum resins, aromatic hydrocarbon resins, alicyclic hydrocarbon resins, low-molecular-weight styrene resins, isoprene resins, alkylphenol resins, etc., but if known, particularly It is not limited.

In addition to the components described above, the sealant resin composition of the present disclosure may optionally contain additives such as slip agents, release agents, antioxidants, heat stabilizers, light stabilizers, pigments, and dyes. can be done. The total content of these additives in the sealant resin composition is preferably 2% by mass or less, more preferably 1% by mass or less, and 0.5% by mass or less. is more preferable and need not be included.

<Ethylene/unsaturated ester copolymer (A): component (A)>
The sealant resin composition of the present disclosure contains an ethylene/unsaturated ester copolymer (A). The ethylene/unsaturated ester copolymer (A) contains structural units derived from ethylene and structural units derived from unsaturated ester.
The ethylene/unsaturated ester copolymer (A) of the present disclosure may be used alone or in combination of two or more.

Examples of the unsaturated ester of the ethylene/unsaturated ester copolymer (A) include vinyl esters such as vinyl acetate and vinyl propionate.
Among these, vinyl acetate is preferable as the unsaturated ester from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane.

The ethylene/unsaturated ester copolymer (A) may contain structural units derived from monomers other than ethylene and unsaturated esters (hereinafter also referred to as “other structural units”).
Other structural units include, for example, unsaturated carboxylic acid esters, unsaturated hydrocarbons (eg, propylene, butene, 1,3-butadiene, pentene, 1,3-pentadiene, 1-hexene, etc.), vinyl sulfate, vinyl Structural units derived from oxides such as nitric acid, halogen compounds (eg, vinyl chloride, vinyl fluoride, etc.), vinyl group-containing primary and secondary amine compounds, carbon monoxide, sulfur dioxide, and the like can be mentioned.
Among these, other structural units are preferably structural units derived from unsaturated carboxylic acid esters. The structural unit that can be counted as the ethylene/(meth)acrylic acid alkyl ester copolymer (B) described later is counted as the ethylene/(meth)acrylic acid alkyl ester copolymer (B), Not included in the saturated ester copolymer (A).

The unsaturated carboxylic acid ester is not particularly limited as long as it can be copolymerized with ethylene and an unsaturated ester, and examples thereof include unsaturated carboxylic acid alkyl esters.
Examples of unsaturated carboxylic acid alkyl esters include alkyl acrylates such as methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate and isooctyl acrylate, methyl methacrylate, ethyl methacrylate and isobutyl methacrylate. and unsaturated carboxylic acid alkyl esters having 1 to 12 carbon atoms, such as methacrylic acid alkyl esters such as dimethyl maleate and maleic acid alkyl esters such as diethyl maleate.

Among these, unsaturated carboxylic acid alkyl esters include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, and n methacrylate. Alkyl esters of acrylic acid or methacrylic acid such as -butyl and isooctyl methacrylate are preferred, and lower alkyl esters of acrylic acid or methacrylic acid (alkyl esters having 2 to 5 carbon atoms) are more preferred.

From the viewpoint of maintaining good sealing strength and suppressing the amount of elution into hexane, the content of other structural units is 0.00 with respect to all structural units of the ethylene/unsaturated ester copolymer (A). 1% by mass to 10% by mass is preferable, 1% by mass to 5% by mass is more preferable, and 0% by mass is acceptable.

The ethylene/unsaturated ester copolymer (A) is 30% by mass or more and 85% by mass based on the total mass of the sealant resin composition from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane. % or less, more preferably 30% by mass or more and 80% by mass or less.

The ethylene/unsaturated ester-based copolymer (A) can adjust the resistance to peeling (seal strength) by adjusting the content of unsaturated ester-derived structural units. From this point of view, the content of the unsaturated ester-derived structural unit is preferably 1% by mass to 40% by mass, preferably 2% by mass, based on the total structural units of the ethylene/unsaturated ester copolymer. It is more preferably ~30% by mass, and even more preferably 5% by mass to 25% by mass.
When the content of the unsaturated ester-derived structural unit is 1% by mass or more, the seal strength is more likely to be obtained, and the stability of the seal strength is more likely to be improved. Further, when the content of the unsaturated ester-derived structural unit is 40% by mass or less, there is a tendency that the stability of the seal strength and the anti-blocking property are excellent.

The melt flow rate (MFR) of the ethylene/unsaturated ester copolymer (A) is 0.1 g/10 min from the viewpoint of maintaining good seal strength, suppressing the amount of elution into hexane, and workability. It is preferably up to 150 g/10 minutes, more preferably 0.5 g/10 minutes to 100 g/10 minutes, even more preferably 1 g/10 minutes to 50 g/10 minutes.
The MFR of the ethylene/unsaturated ester copolymer (A) can be measured at 190° C. under a load of 2160 g according to JIS K7210 (1999) corresponding to ISO 1133:1997.

The ethylene/unsaturated ester copolymer (A) contains a structural unit having a polar group and a structural unit derived from an unsaturated ester.
Further, the ethylene/unsaturated ester copolymer (A) may contain structural units derived from monomers having polar groups other than the unsaturated ester. Other monomers having a polar group include monomers having a polar group such as a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, and an alcoholic hydroxyl group.
Here, the content ratio of the structural unit having a polar group contained in the ethylene/unsaturated ester copolymer (A) was 100 mol% of the structural unit of the ethylene/unsaturated ester copolymer (A). is preferably 1.8 mol % or more and 11 mol % or less, more preferably 1.8 mol % or more and 8 mol % or less.
In addition, the content ratio of the structural unit having a polar group contained in the ethylene/unsaturated ester copolymer (A) means that the ethylene/unsaturated ester copolymer (A) contains It indicates the total content ratio of structural units derived from monomers.

<Ethylene/(meth)acrylic acid alkyl ester copolymer (B): component (B)>
The sealant resin composition of the present disclosure contains an ethylene/(meth)acrylic acid alkyl ester copolymer (B) (wherein the ethylene/unsaturated ester copolymer (A) and ethylene/(meth)acrylic acid Alkyl ester copolymer (B) is different.). The ethylene/(meth)acrylic acid alkyl ester-based copolymer (B) contains structural units derived from ethylene and structural units derived from (meth)acrylic acid alkyl ester.
The ethylene/(meth)acrylic acid alkyl ester copolymer (B) of the present disclosure may be used alone or in combination of two or more.

The ethylene/(meth)acrylic acid alkyl ester copolymer (B) is a copolymer of ethylene and an alkyl ester having 1 or more carbon atoms (preferably 1 to 4 carbon atoms) in the alkyl moiety of acrylic acid or methacrylic acid. It is a coalescence (preferably a random copolymer).
Examples of alkyl esters of acrylic acid or methacrylic acid include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, iso-butyl methacrylate, n-butyl methacrylate and the like.
Among these, a (meth)acrylic acid alkyl ester having an alkyl moiety having from 1 to 4 carbon atoms is preferable in terms of availability, performance and cost balance.

As the ethylene/(meth)acrylic acid alkyl ester copolymer (B), from the viewpoint of maintaining good sealing strength and suppressing the amount of elution into hexane, for example, ethylene/methyl acrylate copolymer, ethylene Ethyl acrylate copolymer, ethylene/n-propyl acrylate copolymer, ethylene/isopropyl acrylate copolymer, ethylene/n-butyl acrylate copolymer, ethylene/isobutyl acrylate copolymer, ethylene/methacrylic acid Methyl copolymer, ethylene/ethyl methacrylate copolymer, ethylene/n-propyl methacrylate copolymer, ethylene/isopropyl methacrylate copolymer, ethylene/n-butyl methacrylate copolymer, ethylene/isobutyl methacrylate copolymer A coalescence or the like is preferable, and at least one of an ethylene/methyl acrylate copolymer and an ethylene/methyl methacrylate copolymer is more preferable.

The ethylene/alkyl (meth)acrylate copolymer (B) may contain structural units derived from monomers other than ethylene and alkyl (meth)acrylate.
That is, the ethylene/(meth)acrylic acid alkyl ester copolymer (B) may contain "another structural unit" as in the ethylene/unsaturated ester copolymer (A) of the present disclosure. The same applies to preferred embodiments of "another structural unit".
As the content of other structural units, from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane, all the structural units of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) 0.1% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, and may be 0% by mass.

The ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 15 masses relative to the total mass of the sealant resin composition from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane. % or more and 70 mass % or less, more preferably 20 mass % or more and 70 mass % or less.

The ethylene/(meth)acrylic acid alkyl ester copolymer (B) can be adjusted in peel resistance (seal strength) by adjusting the content of the (meth)acrylic acid alkyl ester. From this point of view, the content of the (meth)acrylic acid alkyl ester is preferably 1% by mass to 40% by mass based on the total structural units of the ethylene/(meth)acrylic acid alkyl ester copolymer. , more preferably 5% by mass to 35% by mass, and even more preferably 10% by mass to 30% by mass.
When the content of the (meth)acrylic acid alkyl ester is 1% by mass or more, the seal strength is more likely to be obtained, and the stability of the seal strength is more likely to be improved. Moreover, when the content of the (meth)acrylic acid alkyl ester is 30% by mass or less, there is a tendency that the seal strength, the stability of the seal strength, and the blocking resistance are excellent.

The melt flow rate (MFR) of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 0.1 g/10 from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane. min to 150 g/10 min, more preferably 0.5 g/10 min to 100 g/10 min, even more preferably 1 g/10 min to 50 g/10 min.
The MFR of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) can be measured at 190° C. under a load of 2160 g by a method according to JIS K7210 (1999) corresponding to ISO 1133:1997. can.

The ethylene/(meth)acrylic acid alkyl ester copolymer (B) contains (meth)acrylic acid alkyl ester as a monomer constituting a structural unit having a polar group.
Furthermore, the ethylene/(meth)acrylic acid alkyl ester copolymer (B) may contain a structural unit derived from a monomer having a polar group other than the (meth)acrylic acid alkyl ester. Other monomers having a polar group include monomers having a polar group such as a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, and an alcoholic hydroxyl group.
Here, the content ratio of the structural unit having a polar group contained in the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is preferably 7 mol % or more and 10 mol % or less, and more preferably 7.5 mol % or more and 9.5 mol % or less, based on 100 mol % of the constituent units of .
The content ratio of the structural unit having a polar group contained in the ethylene/(meth)acrylic acid alkyl ester copolymer (B) refers to the ethylene/(meth)acrylic acid alkyl ester copolymer (B). It indicates the total content ratio of constituent units derived from monomers having polar groups contained therein.

-Relationship between component (A) and component (B) in sealant resin composition-
The sealant resin composition of the present disclosure contains an ethylene/unsaturated ester copolymer (A) and an ethylene/(meth)acrylic acid alkyl ester from the viewpoint of maintaining good seal strength and suppressing the amount of elution into hexane. The content of the ethylene/unsaturated ester copolymer (A) is 10% by mass or more and 90% by mass or less with respect to the total content (100% by mass) of the system copolymer (B), and The content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 10% by mass or more and 90% by mass or less.
When the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 10% by mass or more, the peel strength is good and the seal strength is excellent. When the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 90% by mass or less, it is possible to prevent the seal strength from becoming too high, resulting in good seal strength. Further, when the content of the ethylene/unsaturated ester copolymer (A) is 10% by mass or more, it is possible to prevent the seal strength from becoming too high, resulting in good seal strength. When the content of the ethylene/unsaturated ester copolymer (A) is 90% by mass or less, the peel strength is good and the seal strength is excellent.
Furthermore, the content of the ethylene/unsaturated ester copolymer (A) is 25% by mass or more and 85% by mass or less, and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is contained. The amount is preferably 15% by mass or more and 75% by mass or less, the content of the ethylene/unsaturated ester copolymer (A) is 30% by mass or more and 80% by mass or less, and ethylene/(meth) More preferably, the content of the acrylic acid alkyl ester copolymer (B) is 20% by mass or more and 70% by mass or less, and the content of the ethylene/unsaturated ester copolymer (A) is 40% by mass or more. More preferably, it is 80% by mass or less, and the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 20% by mass or more and 60% by mass or less.
The total amount of the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) contained in the sealant resin composition is the total amount of the sealant resin composition. It is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

The sealant resin composition of the present disclosure contains structural units having a polar group contained in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B). The total ratio is 5.0 mol% or more and 8.5 mol% or less (however, the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer in the sealant resin composition The total molar amount of the constituent units of coalescence (B) is 100 mol %).
When the total content ratio of structural units having a polar group is 5.0 mol% or more, the seal strength can be prevented from becoming too low, and when it is 8.5 mol% or less, the seal strength can be prevented from becoming too high. Therefore, it is possible to adjust the sealing strength to be good.
In addition, from the viewpoint of obtaining good seal strength, the structural unit having a polar group contained in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) The total content ratio is preferably 5.6 mol % or more and 8.3 mol % or less, more preferably 5.7 mol % or more and 8.0 mol % or less.

In the sealant resin composition of the present disclosure, the total molar amount of structural units of the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 100 mol%. Then, the content ratio X (mol%) of the unsaturated ester-derived structural unit in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) The content ratio Y (mol%) of the structural unit derived from the (meth)acrylic acid alkyl ester in the following formula (1), formula (2) and (3) are preferably satisfied, and it is more preferable to satisfy all of the following formulas (4), (5) and (6).
Y>1 (1)
Y<-0.7X+7.1 (2)
Y>-0.7X+4.4 (3)
Y≧1.8 (4)
Y≤-0.7X+6.8 (5)
Y≧−0.7X+5.2 (6)

-Characteristics of sealant resin composition-
Since the sealant resin composition of the present disclosure exhibits the property that the elution amount in n-hexane is 30 mg/L or less, it can be said that the elution amount in hexane is suppressed. In addition, the peel strength when a high-frequency seal strength test is performed using the sealant resin composition of the present disclosure shows a property of 10 N / 15 mm or more and less than 15 N / 15 mm, so good seal strength is maintained. It can be said.
In addition, the sealant resin composition of the present disclosure preferably has an elution amount in n-hexane of 30 mg/L or less, more preferably 28 mg/L or less.
In addition, the peel strength when a high-frequency seal strength test is performed using the sealant resin composition of the present disclosure is preferably 10 N / 15 mm or more and less than 15 N / 15 mm, and 10 N / 15 mm or more and 14.6 N / 15 mm It is more preferably less than.
The specific methods for measuring the amount of elution with respect to hexane and the peel strength in the high-frequency seal test are the same as those used in Examples described later.
That is, the elution amount for hexane is measured by a test method including at least the following steps:
A step of preparing a test piece comprising a base layer and a seal layer provided on one surface of the base layer and composed of the sealant resin composition;
The test piece is set in a single-sided elution jig, and the single-sided elution jig with the test piece is set so that the amount of n-hexane solvent is 2 mL with respect to the surface area of 1 cm ² of the seal layer of the test piece. A step of immersing in an n-hexane solvent of V [L] and standing at 25 ° C. for 2 hours to obtain an n-hexane extract; and Extracting by distilling off the n-hexane from the n-hexane extract A step of obtaining a residue, measuring the mass M [mg] of the extraction residue, and calculating the extraction amount Z (M/V) [mg/L] of the sealant resin composition into the n-hexane.
Also, the peel strength is measured by a test method comprising at least the following steps:
A step of preparing a test piece comprising a base layer and a seal layer provided on one surface of the base layer and composed of the sealant resin composition;
The test piece is laminated on the HIPS sheet so that the seal layer is in contact with the 0.5 mm thick impact-resistant polystyrene (HIPS) sheet, and a 0.3 mm thick PET sheet is laminated on the test piece and laminated. the process of obtaining a body;
A high-frequency welder having a maximum output of 3 kW and an oscillation frequency of 40.46 MHz was applied to the laminate for 2 seconds at an output of 52% or 54% and a gauge pressure of 0.1 MPa, and welded for 0.5 seconds. , a step of adhering the test piece to the HIPS sheet by cooling for 2 seconds, removing the PET sheet from the laminate, and leaving it in an environment of 23 ° C. for 24 hours; A step of separating the test piece adhered to the HIPS sheet at 300 mm/min as a test piece having a width of 15 mm from the HIPS sheet, and defining the maximum stress observed when separating from the HIPS sheet as the peel strength [N/15 mm].

[Lid material]
The lid material of the present disclosure includes the sealant resin composition of the present disclosure. For example, the sealant resin composition of the present disclosure can be suitably used as a heat-sealing material for plastic containers, especially as an easy-to-open sealing material for a container such as impact-resistant polystyrene or foamed polystyrene and its lid. .

When the sealant resin composition of the present disclosure is used as an easy-open sealing material, it is usually used in the form of being laminated on various substrates.
Examples of the substrate include paper, aluminum, polyester, polyethylene, polypropylene, (impact-resistant) polystyrene, aluminum-deposited polyester, aluminum-deposited polypropylene, silica-deposited polyester, and the like. Such a substrate need not be a single layer, and may be a laminate of two or more layers.
In addition, the lamination method on various substrates is a known method, and is not particularly limited.

[Package]
A package of the present disclosure includes the lid material of the present disclosure and a bottom material to which the lid material is heat-sealed. Moreover, the package of the present disclosure can be used as various packaging materials.
Examples of the form of the package include various containers with easy-to-open seal lids made of a single piece of plastic or a laminated body such as those described above.
In particular, when the sealant resin composition of the present disclosure is used as a sealant between an impact-resistant polystyrene container and a lid material, it is excellent in sealing performance, easy opening performance, and the like.
Furthermore, it can be effectively used for heat sealing not only containers made of polystyrene but also containers made of other materials, such as polypropylene, polyester, polycarbonate, polyvinyl chloride, etc., and lids. Such a container with a lid is used for packaging various foods such as instant noodles, noodles, jelly, pudding, yogurt, mitsumame, sour, tofu, lactic acid drinks, Japanese sweets, processed meat, medicines, medical containers, toners, and the like. can be used.

EXAMPLES Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples as long as the gist thereof is not exceeded. The MFR value shown below is a value measured under the conditions of 190° C. and a load of 2160 g by a method based on JIS K7210 (1999) corresponding to ISO1133:1997.

[Examples 1 to 11, Comparative Examples 1 to 12]
The details of the components used to prepare the sealant resin composition are as follows.

<1. Ethylene/unsaturated ester copolymer (A)>
・(EVA-1):
Type: Ethylene-vinyl acetate copolymer "V421 (trade name, manufactured by DuPont Mitsui Polychemical Co., Ltd.)"
Content of vinyl acetate structural unit (VA content): 11.3 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 4g/10min (EVA-2):
Type: Ethylene-vinyl acetate copolymer “EV450R (trade name, manufactured by DuPont Mitsui Polychemical Co., Ltd.)”
Content of vinyl acetate structural unit (VA content): 7.1 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 15g/10min (EVA-3):
Type: Ethylene-vinyl acetate copolymer "EV550 (trade name, manufactured by DuPont Mitsui Polychemical Co., Ltd.)"
Content of vinyl acetate structural unit (VA content): 5.0 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 15g/10min (EVA-4):
Type: Ethylene-vinyl acetate copolymer "BRV72 (trade name, manufactured by Mitsui DuPont Polychemicals)"
Content of vinyl acetate structural unit (VA content): 1.9 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 23.5g/10 minutes

<2. Ethylene/(meth)acrylic acid alkyl ester copolymer (B)>
・(EMA-1):
Type: Ethylene-methyl acrylate copolymer "trade name, ElvaloyAC 12024S (manufactured by DuPont)"
Content of constituent units of methyl acrylate (MA content): 9.3 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 20g/10min (EMA-2):
Type: Ethylene-methyl acrylate copolymer “ElvaloyAC 1820 (trade name, manufactured by DuPont)”
Content of constituent units of methyl acrylate (MA content): 7.5 mol%
MFR (JIS K7210-1999, 190°C, load 2160g) 8g/10min

<3. Additive>
・Slip agent (PEG): polyethylene glycol (manufactured by Nippon Fine Chemical Co., Ltd.)
・Releasing agent (ELA): Erucamide (manufactured by NOF Corporation)

<4. Tackifier>
・ Tackifier resin: alicyclic saturated hydrocarbon resin “Arcon AM-1 (trade name, manufactured by Arakawa Chemical Industries, Ltd.)”

-Preparation of sealant resin composition-
Melt each component at a resin temperature of 150 ° C. with a 65 mmφ single screw extruder (manufactured by Nakatani Machinery Co., Ltd., L / D = 26, screw type: tip dulmage flight screw) so as to have the composition shown in Table 1 below. The mixture was kneaded to prepare a sealant resin composition.
For example, in Example 1 in Table 1, 20% by mass of (EMA-1) and 80% by mass of (EVA-2) with respect to the total mass of (EMA-1) and (EVA-2) described above, 0.09% by mass of a releasing agent and 0.06% by mass of a slip agent, and the total content ratio of structural units having a polar group contained in (EMA-1) and (EVA-2) (provided that The total molar amount of EMA-1 structural units and EVA-2 structural units in the composition is 7.5 mol %).

-Preparation of test piece for evaluation-
A sealant resin composition having the composition shown in Table 1 was processed using a 40 mmφ single extrusion laminator (manufactured by Tanabe Plastics Machinery Co., Ltd., L/D = 32) at an extruder die outlet resin temperature of 220 ° C. and a take-up speed of 30 m / min. , Under extrusion conditions such that the thickness of the seal layer made of the sealant resin composition after molding is 20 μm, the sealant resin composition is extruded from the T die to the base layer (AL layer (20 μm) / PE layer (15 μm) (2-layer laminate) was melt-extruded on the PE layer and laminated into a film.
This film-like laminate was used as a test piece for evaluation.

[evaluation]
-Peel strength in high frequency seal strength test (vs. HIPS seal strength)-
The peel strength in the high frequency seal strength test was measured by the following method. The seal layer side of the test pieces obtained in Examples and Comparative Examples was placed in contact with a 0.5 mm thick HIPS (high-impact polystyrene) sheet (manufactured by RP Topla Co., Ltd., trade name: NOASTIC-M). It was laminated on the HIPS sheet, and a 0.3 mm thick A-PET sheet (manufactured by RP Topla Co., Ltd., trade name: NOACRYSTAL-V) was placed on the AL layer of the test piece.
The resulting laminate was applied with a high-frequency welder (maximum output: 3 kW, oscillation frequency: 40.46 MHz) (manufactured by Seidensha Co., Ltd.) at an output of 52% or 54% and 0.1 MPa (gauge pressure). Sealing was performed with a pressing time of 2 seconds, a welding time of 0.5 seconds, and a cooling time of 2 seconds. (The A-PET sheet used for sealing was removed immediately after sealing.)
Next, in an environment of 23° C., the test piece (15 mm wide test piece) was separated from the HIPS sheet at a tensile speed of 300 mm/min, and the maximum stress was calculated as the seal strength (N/15 mm) against the HIPS sheet.

A peel strength of 10 N/15 mm or more measured by the above method is practically acceptable, and a peel strength of less than 15 N/15 mm is preferable from the viewpoint of easy peelability.

-Hexane extraction test-
A hexane extraction test was performed by the following method. Three test pieces of 15 cm×15 cm were cut out from the test pieces obtained in Examples and Comparative Examples so as to secure a circle of 100 cm ² . Next, the target area of the test piece (total of 3 pieces) was set to 300 cm ² , and each test piece was set so that the seal layer side faced up (100 cm ² /unit for 3 cars). The jig for single-sided elution was the one shown in the figure on page 34 of the document "Specifications and Standards for Apparatuses, Containers and Packaging and Their Test Methods" (supervised by Yoko Kawamura, Standards Examination Section, Food Safety Department, Pharmaceutical and Food Safety Bureau, Ministry of Health, Labor and Welfare). .
Then, the jigs for single-sided elution with the test pieces set were placed in three 300 mL graduated cylinders, 200 mL each of n-hexane solvent at 25° C. was poured thereinto, and each was allowed to stand at 25° C. for 2 hours. After 2 hours, the resulting n-hexane extract (600 mL in total) was collected in a 1 L beaker, and transferred to a 150 mL Soxhlet flask with a constant weight (constant weight means an empty flask after drying at 105°C for 2 hours, cooling for 30 minutes, and measuring the weight repeatedly, the weight change should be 0.5 mg or less). After that, the solvent was distilled off by a rotary evaporator (a total of 600 mL of hexane was distilled off in several batches).
After drying at 105° C. for 2 hours, it was cooled in a desiccator for 30 minutes. The soxhlet flask containing the extraction residue was then weighed in _m2 .
Also, as a blank, the weight m1 of _an empty Soxhlet flask was measured. Here, the weight m ₁ of the empty Soxhlet flask was measured by operating in the same manner as the weight m ₂ measurement, except that 600 mL of n-hexane was used instead of 600 mL of n-hexane extract. The extraction amount Z [mg/L] into n-hexane was calculated from the following formula.
Z={(m ₂ −m ₁ )×1000}/600
Z: Extraction amount to hexane [mg/L]
m ₁ : weight of empty soxhlet flask [mg]
m ₂ : Weight of Soxhlet flask containing extraction residue [mg]

The hexane extraction amount (that is, the elution amount into hexane) measured by the above method is practically acceptable when it is 30 mg/L or less.

As can be seen from Table 1, the sealant resin compositions of Examples exhibited good seal strength and suppressed elution into hexane. Furthermore, Examples 1 to 11 satisfied all of the above formulas (1) to (6).
On the other hand, the sealant resin composition of the comparative example did not satisfy the evaluation criteria in at least one of the seal strength and the amount of elution into hexane.
The disclosure of Japanese Patent Application No. 2018-067435 filed on March 30, 2018 is incorporated herein by reference in its entirety.
All publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. incorporated herein by reference.

Claims (10)

an ethylene/unsaturated ester copolymer (A);
and an ethylene/(meth)acrylic acid alkyl ester copolymer (B) different from the ethylene/unsaturated ester copolymer (A),
With respect to the total content of the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B), the ethylene/unsaturated ester copolymer The content of (A) is 10% by mass or more and 90% by mass or less, and the content of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 10% by mass or more and 90% by mass or less. can be,
When the total molar amount of the structural units of the ethylene/unsaturated ester copolymer (A) and the structural units of the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 100 mol%,
The total content ratio of structural units having a polar group contained in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester copolymer (B) is 5.0 mol%. A sealant resin composition having a content of 8.5 mol % or less. 2. The sealant resin composition according to claim 1, wherein the ethylene/unsaturated ester copolymer (A) is an ethylene/vinyl acetate copolymer. 3. The sealant resin composition according to claim 1, wherein the ethylene-(meth)acrylic acid alkyl ester copolymer (B) has 1 or more and 4 or less carbon atoms in the alkyl moiety. 4. The sealant resin composition according to any one of claims 1 to 3, wherein the content of the tackifying resin is less than 1% by mass. The content ratio X (mol%) of the unsaturated ester-derived structural unit in the ethylene/unsaturated ester copolymer (A) and the ethylene/(meth)acrylic acid alkyl ester-based copolymer with respect to the total molar amount Claim 1, wherein the content ratio Y (mol%) of structural units derived from (meth)acrylic acid alkyl ester groups in the coalescence (B) satisfies all of the following formulas (1), (2) and (3). The sealant resin composition according to any one of claims 4 to 4.
Y>1 (1)
Y<-0.7X+7.1 (2)
Y>-0.7X+4.4 (3) The sealant resin composition according to claim 5, which satisfies all of the following formulas (4), (5) and (6).
Y≧1.8 (4)
Y≤-0.7X+6.8 (5)
Y≧−0.7X+5.2 (6) The sealant resin composition according to any one of claims 1 to 6, wherein the amount of extraction into n-hexane measured by a test method including the following steps is 30 mg/L or less:
A step of preparing a test piece comprising a base layer and a seal layer provided on one surface of the base layer and composed of the sealant resin composition;
The test piece is set in a single-sided elution jig, and the single-sided elution jig with the test piece is set so that the amount of n-hexane solvent is 2 mL with respect to the surface area of 1 cm ² of the seal layer of the test piece. A step of immersing in an n-hexane solvent of V [L] and standing at 25 ° C. for 2 hours to obtain an n-hexane extract; and Extracting by distilling off the n-hexane from the n-hexane extract A step of obtaining a residue, measuring the mass M [mg] of the extraction residue, and calculating the extraction amount Z (M/V) [mg/L] of the sealant resin composition into the n-hexane. The sealant resin composition according to any one of claims 1 to 7, wherein the peel strength measured by a test method including the following steps is 10 N / 15 mm or more and less than 15 N / 15 mm:
A step of preparing a test piece comprising a base layer and a seal layer provided on one surface of the base layer and composed of the sealant resin composition;
The test piece is laminated on the HIPS sheet so that the seal layer is in contact with the 0.5 mm thick impact-resistant polystyrene (HIPS) sheet, and a 0.3 mm thick PET sheet is laminated on the test piece and laminated. the process of obtaining a body;
A high-frequency welder having a maximum output of 3 kW and an oscillation frequency of 40.46 MHz was applied to the laminate for 2 seconds at an output of 52% or 54% and a gauge pressure of 0.1 MPa, and welded for 0.5 seconds. , a step of adhering the test piece to the HIPS sheet by cooling for 2 seconds, removing the PET sheet from the laminate, and leaving it in an environment of 23 ° C. for 24 hours; A step of separating the test piece adhered to the HIPS sheet at 300 mm/min as a test piece having a width of 15 mm from the HIPS sheet, and defining the maximum stress observed when separating from the HIPS sheet as the peel strength [N/15 mm]. A cover material comprising a substrate and the sealant resin composition according to any one of claims 1 to 8. The lid material according to claim 9;
and a bottom material to which the lid material is heat-sealed.